The present invention relates to an endovascular prosthesis and to a method of forming the endovascular prosthesis.
Surgical procedures in which a cardiovascular prosthesis is implanted into a patient""s blood vessel are common in treating many vascular disorders. For example, one common type of cardiovascular prosthesis is an endovascular prosthesis that is used to strengthen a blood vessel wall in the location of an aneurysm, or to open an occlusion in a blood vessel.
A typical endovascular prosthesis includes a flexible, tubular member, made of fabric or PTFE, that may be anchored with sutures or carried by one or more support structures known as stents. Generally, each stent is formed from a material having an elasticity sufficient to permit radial expansion of the stent and having a strength sufficient to prevent radial collapse or burst. Such stents are typically formed from stainless steel, titanium, Nitinol, or a suitable plastic.
A common endeavor in the field of cardiovascular prosthetics is to increase the patency rate of prostheses. Thrombosis and platelet deposition on surfaces of a cardiovascular prosthesis reduce the patency rate of the prosthesis. For example, thrombosis and platelet deposition within an endovascular prosthesis may occlude the conduit defined by the endovascular prosthesis.
Many factors contribute to thrombosis and platelet deposition on the surfaces of known cardiovascular prosthesis. The most common factors are dependent upon the material or materials forming the inner surface of the conduit of the endovascular prosthesis. Typically, thrombosis and platelet deposition begin to occlude the conduit of the endovascular prosthesis when the material or materials forming the conduit of the endovascular prosthesis are foreign to the patient""s body. A thrombus begins to form on the inner surface of the conduit of the endovascular prosthesis and extends annularly about the inner surface of the conduit. Eventually, the thrombus can severely restrict blood flow through the conduit defined by the endovascular prosthesis and, if left untreated, can completely occlude the conduit.
Additionally, thrombosis and platelet deposition may occur as a result of irregularities on the inner surface of a cardiovascular prosthesis. The irregularities may be formed by the structure of an inner stent that is used to support the cardiovascular prosthesis, or may be formed by the inner surface of the flexible member used for the prosthesis.
The present invention is an apparatus for grafting of a blood vessel or other portion of the cardiovascular system. The blood vessel has an inside surface that defines a conduit for directing blood flow. The apparatus comprises an expandable support member having inner and outer surfaces. The outer surface of the expandable support member is for engaging and adhering to the inside surface of the blood vessel. A layer of biological tissue is attached to the inner surface of the support member. The layer of biological tissue has an uninterrupted inwardly facing surface for extending confluently with the inside surface of the blood vessel to provide resistance to thrombosis and platelet deposition as blood flows through the conduit.
According to one aspect of the invention, the layer of biological tissue is selected from the group consisting of peritoneum, pleura, and pericardium.
In a further aspect of the invention, a graft for a blood vessel is provided. The blood vessel has an inside surface that defines a conduit for directing blood flow. The graft comprises a layer of biological tissue having an uninterrupted inwardly facing surface for extending confluently with the inside surface of the blood vessel to provide resistance to thrombosis and platelet deposition as blood flows through the conduit.
According to another aspect of the present invention, the layer of biological tissue comprises an inner lining of a serous membrane that is supported by an outer lining of associated fascia. The outer lining of associated fascia serves as a structural support for the inner lining of serous membrane.
The present invention also provides a method for forming a graft for insertion in a blood vessel. The blood vessel has an inside surface that defines a conduit for directing blood flow. According to the inventive method, an expandable support member having inner and outer surfaces is provided. The outer surface of the support member is for engaging and adhering to the inside surface of the blood vessel. A layer of biological tissue having an uninterrupted inwardly facing surface for extending confluently with the inside surface of the blood vessel to provide resistance to thrombosis and platelet deposition as blood flows through the conduit is also provided. The layer of biological tissue is molded into a desired shape. The layer of biological tissue is attached to the inner surface of the support member.
In yet another aspect of the present invention, a method for preparing a patch for insertion in a blood vessel is provided. The blood vessel has an inside surface that defines a conduit for directing blood flow. According to the method, a layer of biological tissue comprising an inner lining of a serous membrane supported by an outer lining of associated fascia is harvested. The inner lining of serous membrane has an uninterrupted inwardly facing surface for extending confluently with the inside surface of the blood vessel to provide resistance to thrombosis and platelet deposition as blood flows through the conduit. The layer of biological tissue is molded into a desired shape. The layer of biological tissue is packaged in a sterile, biological medium and stored within a vacuum-packed container.